Switch S1 (audio input)
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Unbalanced 600 ohms input Z
S1-5 ON balanced/unbalanced (unbalanced)
S1-4 OFF 8/600 ohms primary (600 ohms)
S1-3 ON 8/600 ohms primary (600 ohms)
S1-2 ON direct/transformer coupled (transformer)
S1-1 OFF direct/transformer coupled (transformer)
Note: one and only one of (1,2) should be on (direct/transformer coupled).
Note: one and only one of (3,4) should be on (8/600 ohms primary).
Ground ring of Rcvr Audio jack for unbalanced input.
Switch S2 (AFSK output)
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Unbalanced High Level (regenerate), no DC isolation
S2-5 OFF (default on)
S2-4 ON (on)
S2-3 OFF (off)
S2-2 ON (off)
S2-1 ON (on)
S3 AFSK Keying Source, echo
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S3-5 ON Rx out source (Rx out on RxD) (default on)
S3-4 OFF Rx out source (Rx out on RxD) (off)
S3-3 OFF Rx out source (Rx out on RxD) (off)
S3-2 ON AFSK source (both TxD and RxD) (off)
S3-1 OFF AFSK source (both TxD and RxD) (on)
Note: one and only one of (1,2) should be on (AFSK source).
Note: one and only one of (3,4,5) should be on (Rx out source).
S4 AFSK Tone enable
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S4-5 OFF AFSK enable during both Rx and Tx (default on)
S4-4 OFF FSK polarity (normal) (off)
S4-3 ON FSK polarity (normal) (on)
S4-2 OFF FSK output level (open collector) (off)
S4-1 OFF FSK output level (open collector) (off)
Note: at most one of (1,2) should be on (FSK output level).
Note: one and only one of (3,4) should be on (FSK polarity).
Rear panel connector:
Pin 1 AFSK out
Pin 4 Gnd out
NOTE: firmware (U10 and U11) is V1.4. (originally apparently V1.2)